1. Technical Field
The present invention relates to an electronic device, and a manufacturing method of an electronic device, in which a stacked body is bonded to a drive substrate including a drive element and a wiring related to driving of the drive element formed therein.
2. Related Art
An electronic device includes a drive element such as a piezoelectric element that is deformed in response to an applied voltage, and the electronic device is applied to various types of devices, sensors, or the like. For example, a liquid ejecting apparatus ejects various types of liquid from a liquid ejecting head using the electronic device. Examples of the liquid ejecting apparatus include an image recording apparatus such as an ink jet printer and an ink jet plotter, but in recent years, the liquid ejecting apparatuses has also been applied to various manufacturing apparatus, by taking advantage of features that a very small amount of liquid can be accurately landed at a predetermined position. For example, the liquid ejecting apparatus has been applied to a display manufacturing apparatus that manufactures a color filter for a liquid crystal display, or the like, an electrode forming apparatus that forms electrodes in an organic electro luminescence (EL) display, a field emission display (FED), or the like, and a chip manufacturing apparatus that manufactures a bio-chip (a biochemical element). Then, a recording head for the image recording apparatus ejects liquid ink, and a color material ejecting head for the display manufacturing apparatus ejects respective color material solutions of Red (R), Green (G), and Blue (B). Further, an electrode material ejecting head for the electrode forming apparatus ejects liquid electrode materials, and a bio-organic material ejecting head for the chip manufacturing apparatus ejects a bio-organic material solution.
The liquid ejecting head includes an electronic device in which a flow path substrate including a pressure chamber formed thereon in communication with a nozzle, a piezoelectric element (a type of a drive element) causing a pressure fluctuation in liquid inside the pressure chamber, a sealing plate (or also referred to as a protection substrate) provided and spaced from the piezoelectric element, and the like are stacked. In recent years, a technique of providing a drive circuit related to the driving of an actuator such as a piezoelectric element on a sealing plate has also been developed. Then, a technique is proposed in which this substrates are bonded with each other by adhesive (adhesive resin) made of photosensitive resin in a state where there is a space therebetween. In addition, a structure is adopted in which substrates are stacked by a photosensitive resin in order to correspond to the high density and miniaturization of a wiring, in a semiconductor package of a micro electro mechanical systems (MEMS) such as various sensors. Moreover, since there is a need for such high accuracy and low power consumption, in addition to the miniaturization of the package in this type of MEMS, gold (Au) having a low electric resistance for wirings related to driving of the drive circuit and having excellent ductility is preferably employed as a material. For example, in an ink jet printer which is disclosed in JP-A-2014-34114, gold is used as a wiring related to driving of a piezoelectric element which is a driving element. Then, a sealing plate is bonded to the substrate on which the piezoelectric element, the wiring, and the like are formed, through an adhesive.
However, there is a problem in that the adhesive strength caused by an adhesive becomes weak in the wiring portion, and the adhesive tends to be peeled off, when employing Au as a wiring in the configuration of bonding the substrates to each other by using an adhesive. In this regard, the configuration of JP-A-2014-34114 secures the adhesive strength by obtaining an effective bonding surface area by the adhesive at a portion other than the wiring. However, if the bonding strength in a wiring portion is weak, a bonding reliability is not sufficient, and in particular, a sufficient adhesive strength is not obtained in a configuration in which wiring is highly densified on the substrate and a large surface area is occupied.